Inverters are frequently used as a buffer of a signal. However, the available voltage headroom of a buffer may not be sufficient in modern electronic systems which operate with low supply voltage. For a buffer with low voltage headroom, the noise, which is generated from internal circuits or injected from external circuits, at the input of the buffer may directly introduce jitter or glitches at the output, and lead to system malfunction. The noise generated from internal circuits or injected from external circuits may not be scaled in accordance with the voltage headroom. Therefore, a buffer operated with low supply voltage and with suppressed jitter and glitches is highly desirable in modern electronic systems.